Alternating-current electric meter.



v G. NORTH. ALTERNATING CURRENT ELECTRIC METER.

APPLICATION FILED JUNE 21, 1911.

1 116372, Patented Nov. 10, 1914.

Fig.1. Fig.2.

ATTORN s rnrnnr onion GELBEET NORTH, OF STRETFORD, ENGLAND, ASSIGNOR TO WESTINGHOUSE ELECTRl AND FLANUFACTUBING COMPANY, A CORPORATION OF PENNSYLVANIA.

ALTERNATING-CUEBENT ELECTRIC METER.

Specification of Lettersratent.

Patented Nov. 10, 1914.

Application filed June 21, 1911. Serial No. 634,584.

To all whom it may; concern:

Be it known that l, GILBERT NORTH, a. subject of the King of Great Britain, and a resident of Stretford, in the county of Lancaster, England, have invented it new and useful improvement in Alternating-Current Electric ltleters, of which the following is a specification.

This invention relates to alternating current electric m rers end in particular to instruments of this class, known as induct-ion type meters, in which the magnetic flux due to coils connected in series with and in shunt to the circuit, the energy supplied to which is required to be measured, act upon an armature shaped to a figure of revolution usually a circular disk. 7 1

The object of the inventionis to construct an eiiicient meter of this type having good working characteristics which shallbe sim-f ple and cheap to manufacture, of very small dimensions and light weight. The improved meter of the present invention in common with other well-known meters of the class above mentioned, is provided with two iron circuits for the magnetic flux due to the shunt coil, one of these circuits being arranged so that the flux therein passes through the meter disk 01',- arniature and the other, generally known as the leakage path, being provided with a suitable air gap or the flux in this path not passing through the meter disk. The series coil or coils are also rovided with iron circuits and substantial y the whole of the flux due to the series winding passes through the meter d sh. in order to reduce the dimensions of the meter far as possible, it is necemary to reduce the reluctance of the leakee c path for the shunt flux, but to maintain a large driving torque the reluctance of the path "for that portion of the shunt flux which passes through the meter armature must also be reduced. At the same time in order toobtein u satisfactory load curve. the

the path for the series flux.

reluctance or should be high, so to reduce the damping eirect oi the series poles on the disk.

" o present invention the re Accorrun ctance or e path of the shunt flux at the embodying the invention.

frame of of the instrument is arranged to be decreased without correspondingly decreasing the reluctance of the path of the series flux.

The invention is illustrated in the accompanying drawings, of which Figures 1 to 6 inclusive are diagrammatic views illustrating various constructional forms of the cores and windings of meters Referrin now to Fig. 1 the shunt core of the meter 15 indicated at l and is substantially E-shaped in form, the shunt coil 2 of the meter surrounding the central limb 3 of the c'ore which is rovided with lateral projections 4, the en s of which are separated by small air gaps 5 from the outer limbs 6.

Two extensions 7 projecting from the portions 4 and adjacent to the meter disk'8 -.constitute the series core of the instrument,

the series coils 9 being wound in opposite directions around the projections 7 The paths oi the fluxes due to the series coils 9 and the shunt coil 2 also include a convex projection 10 of magnetizable material situated below the meter disk 8 and attached to the meter case or frame. The paths of the fluxes clue to the shunt coil 2 are indicated in the figure by the dotted lines a, b, and the path of tits: flux due to theseries coils 9 by the full li e c, it being understood that the magnetic pircuit of the flux traversing the path I) is completed through the casing or the meter. As will be observed the arrangement of the parts of the core of the shunt and series windings 2 and 9 is such that while the path a, traversed by the leakage flux due to the shunt coil, has a low magnetic reluctance, the, part of the flux passing through the meter disk 8 along the path I) traverses the portions 7 and 10 of the core and the two air gaps between these portions in parallel with one another so that the reluctance of the magnetic circuit of'this flux high so that the damping effect of the series poles is reduced and a satisfactory iced curve for the meter is thereby obtained,

Referring now to Fig. 2 a. modification of the arrangement shove describedis ilies ireted in. which the reluctance of she cir- 'cuit of that poriion of shunt fiiix troversing the disk 8 of the meter is further reduced by the provision orifan edczitionai pr jection ll sttachedio she cenirel limb 2 of the shims core 1 opposite to the projection 10. The provisionof the projection 11 evidently provides a third path for the shunt flux passing through the meter disk in'oddition to the paths provided by she projections 7, the path of the series fiuzr remsining unalierei;

Fig. 3 illustrates a modification ofvthe arrangemeni; of Fig. 2 in which the core 1 is of such shape 1: Lat-the leakage flux traverses a single paths the plane of which is at right angles to the plane of the path a of the series flux. v

The number of poles through which the main shunt magnetic fiux passes is not him ited to three, and the series coil. may be Wound on all or some only of said poles. For example, in the construction shown in Fig. 4, four-projections u on which the series coils 9 of the inc sor are Wound; are proviiieii, the projection '10 having these limbs iocatsd opposite to the spaces heiween each of the projections 7.

In the above modifications ishe poles oi the seiol iron pert may be rounded on that side facing the series poles ii neoessery in order to properly proportion the size of the air gap for the series flux.

eferringnow to Fig. 5 a further constructional form of the invention is iilusirate-:1 in which the series coils 9 of the meher are Wound upon the outer limbs 11 of 3, separate E-shaped core 12, the central limb 13 of which serves to d reaso the reluctance of the path 5 of the shims flux of the meter in a similar manner to the projection 10 of the construction shows in the The path 0 or" the series flue: in this case in cluties the air gaps between the centre limb .3 of the shunt core ,i-end the outer limbs of the core '12 in series with one an other and is therefore relatively high.

Referring now to Fig. 6 a morlificetion of the arrangement of Fig. 5 is illustrated is all, the coninvention, the

in rediIciiifg-the passes into the meter disk ismade ss large as possible compared with the secfiion of they pert on which the shunt" coil is wound. Thus the latter section need be nov greater than is necessary to avoid saturation of the. iron, and spondingly-small dimensions.

claim as my invention: 1. As aiiernsiiiig curreni; motordneser comprising a voitsge'w w able core leg siirroiiiided by she voltage winding and a part izhat extends seijeceni so, has is erstei'i by e smaii sir ep from, the side 6.. the leg, she said eg provideci with session that projects h yo core part, a load. i" tsin of the poles s other of the poles coo voltage winding.

2. An eiterneiisg cu motor-meter comprising a voltage win megnetiw able core having a leg surrsomieci' by the voltage winding. and a para; that extends adjacent to, ions is se erate; by a smell sir gap from, the side or she said ieg, the said leg being provioied with e tension test projects iseyon said iafersi core pet is extends irassierseiy with re spect thereto a iced Winding serrour'uiing certain of he poles of said extension while another or the poise constitutes a. poieior the voltage-winding.

In testimony whereof, I have heseunto subscribe& my name this eighth day of June, 1911.

GILZBEET NORTH. Wiinesses:

Lsoeow Cums BENTON. EDWIN EDGAR.

fihe shun; core 1 is flue" follows a path a on of the "poles through which the'shcntmagnetic-flux the shunt coil will be M con-e lath for the main amt winding, but;

ah is reducedss' 1 I,

e msgneeiz- 

